Electrical pulsing circuit



May 20,l 1969 a. H. GRIMME ET AL 3,445,678

l ELECTRICAL PULSING CIRCUIT Filed Oct. 24, 1967 M C 9 2 \C S// o m I A y, m o o @I r 7 c/ P 3 f T b .m 2 v K1 y 2 Dlgs INVENTORS.

United States Patent O U.S. Cl. 307-132 2 'Claims ABSTRACT OF THE DISCLOSURE An electrical circuit using the charging and discharging of capacitors thru resistors to control the operation of two relays. One of the contacts of one of the relays provides a pulsating output voltage, dependent on the operation of its relay.

Dedicatory clause The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

Background of the invention This invention is in the field of pulse generators. In particular, the invention is a circuit in which alternate pulses may be independently varied in length. Such pulse generators find use in telegraph or other test systems, when it is desirable to have a means for generating marks and spaces of different time durations. Many different circuits are known capable of producing variable-length marks and spaces. One known manner is the use of counting chains in which the number of elements in the chain may be Varied, for different pulse durations. Another manner is the use of electrical flip-flops using vacuum tubes or transistors. The known systems have the disadvantages of being complex and/ or expensive.

Summary of the invention This invention is a system for producing the pulses discussed above, but with a simple and inexpensive circuit. The invention includes two relays having cross-connected contacts, with resistor-capacitor combinations determining the on and ofi times of the relays. The on and off times may be readily varied by paralleling various combinations of capacitors, with rotary switches.

An object of the invention is to provide a novel pulse generating circuit.

Another object of the invention is to provide a pulse generating circuit employing relays controlled by timedelay, resistor-capacitor networks.

Yet another object is to provide a circuit capable of producing a symmetrical or non-symmetrical rectangular wave.

Brief description of the drawing The single drawing figure shows a schematic diagram of the inventive system.

Description of the preferred e'mbodimdnt Referring to the drawing ligure, two relays K1 and K2 are provided, each relay having respective contacts kla-kld and, k2a and k2b. The circuit also includes two rotary switches (S1 and S2), each switch having two ganged banks. Connected to various fixed contacts of the switches are capacitors C1-C5 (for switch S1) and C6- C (for switch S2). The movable contacts of each switch are connected to a resistor. The combination of resistor `and capacitor(s) determines the operating times of the relays.

Cil

Patented May 20, 1969 ICC Operation The circuit will begin generating pulses when a positive voltage is applied to the terminal labeled BIAS. With the various relay contacts in the positions shown in the drawing, relay K1 will be energized thru contacts k2a. Capacitor C1 starts to charge thru contact klb and resistor R2. When relay K1 energizes, contacts kla and klb open, and contacts klc and kld close. The output terminal (P) receives a momentary voltage thru contact kla until relay K1 picks-up. With contact klb open, and contacts k2a and kld closed, C1 charges thru k2a, kld and resistor R2. With contact klc closed, relay K2 energizes. When K2 energizes, k2a opens and kZb close, and capacitor C6 charges thru k2b and R3. With k2a open, relay K1 drops-out, after a time delay from the discharge of C1 thru R4, diode D2, kld, and K1. Relay K1 cannot pickup again while relay K2 is energized, since contacts k2a is open. With K1 dropped-out, contact kLc is open, and relay K2 holds-in until capacitor C6 discharges thru resistor R5, diode D3, contact k2b` and relay K2. When relay K2 drops-out, contact k2a closes and relay K1 again picksup. As long as relay K1 was dropped-out, contacts Kla and Klb were closed, and voltage was applied to output terminal P. With reactivation of relay K1, the cycle starts again. It should be noted that initial application of the bias voltage causes a momentary output at P. When relay K1 picks-up, this momentary output ceases, and the circuit settles down and begins to generate the desired pulses.

The pulse ofi (space) time (when voltage at P20) is determined by the capacitance value selected by switch S1, and by the value of resistor R4. The pulse on (mark) time is determined by the capacitance value selected by switch S2 and by the value of resistor R5. If the coils of relays K1 and K2 are assumed to have resistances, the values of these resistances will be added to the value of resistors R4 and R5, respectively. Diode D1 and resistor R1 eliminate any negative spikes which might tend to appear at P.

While a specific embodiment of the invention has been disclosed, other embodiments may be obvious to one skilled in the art, in light of the disclosure.

What is claimed is:

1. A pulse generating circuit including first and second relays; a voltage source; rst and second means for varying the energization time of each of said relays; and an output terminal; wherein said first relay has a coil, first and second normally closed contacts, and first and second normally open contacts; said second relay has a coil, a normally closed contact, and a normally open contact; said output terminal is connected to one side of said first normally closed contact of said first relay, with the other side of said last named contact connected to said voltage source; said second normally closed contact of said first relay connected between said voltage source and said means for varying; said first normally open contact of said first relay connected between said voltage source and one side of said coil of said second relay, said normally closed contact of said second relay having one side connected to said voltage source, and the other side connected to said one side of said coil of said first relay; said second normally open contact of said first relay connected between said other side of said normally closed contact of said second relay and said first means for varying; said normally open contact of said second relay connected between said second means for varying and one side of said coil of said second relay; each of said means for varying including a first resistor; capacitor means having one side connected to one said first resistor, with the other side of said capacitor means connected to a common point; the other side of each of said coils of said relays connected to said common point; each of said capacitor means including plural capacitors, and switch means for selectively paralleling ones of said capacitors; each of said means for varying further including a second resistor and a diode in parallel with said rst resistor, said output terminal connected to said iirst normally closed contact of said rst relay, each of said diodes being connected in series with each of said second resistors and in opposite polarity to said voltage source.

2. The circuit as defined in claim 1 further including a series-connected resistor-diode combination, connected between said output terminal and said common point, said diode of said combination being connected in opposite polarity to said voltage source.

References Cited ROBERT K. SCHAEFER, Primary Examiner.

10 T. B. JOIKE, Assistant Examiner.

U.S. C1. XR. 

